Optical finger navigation device
View Patent ↗An optical finger navigation (OFN) device for use in handheld portable devices is presented. The OFN device may include a light source, a sensor, a lens holder integrated with a light guide system and a molded lead frame. The lens holder may include a lens receiving region for receiving the lens, a light guide system for directing light emitted by the light source towards the navigation surface. The light guide system may include a slanted wall that may be coated with a light reflective material.
1. An optical finger navigation device comprising:
a light source configured to emit light;
a sensor configured to receive light from a navigation surface;
a molded lead frame comprising a base with a plurality of pins;
a lens configured to direct light from the navigation surface toward the sensor; and
a lens holder molded to form a unitary structure, the lens holder comprising:
a lens receiving region configured to receive the lens;
a light guide system for directing the emitted light towards the navigation surface in a light path that extends from the light source to the navigation surface; the light guide system comprising an aperture system that defines a cavity that passes through the lens holder; that is aligned with the light source; and that is configured to direct the emitted light from the light source towards the navigation surface in the light path; and
a plurality of through holes, wherein the plurality of pins and the plurality of through holes mate together via a heat staking process, and wherein each of the plurality of pins passes through a corresponding through hole of the plurality of through holes and an end portion of the each of the plurality of pins is protruded from the corresponding through hole, and during the heat staking process the plurality of pins is heated and the end portion of each of the plurality of pins is deformed into a protrusion that has a diameter larger than a diameter of the plurality of pins such that the protrusion becomes a lock structure and the plurality of pins is locked within the plurality of through holes, respectively.
2. The optical finger navigation device of claim 1 , wherein the cavity comprises an input opening nearest the light source where the emitted light enters the cavity and an output opening nearest the navigation surface where the emitted light exits the cavity, the aperture system that defines the cavity having at least one surface extending between the input and the output of the cavity, the at least one surface being slanted at an angle to reflect at least a portion of the emitted light towards the navigation surface, wherein there is no illumination lens located in the entire light path between the light source and the navigation surface, and wherein the at least one slanted surface is coated with a light reflective material.
3. The optical finger navigation device of claim 1 , wherein the lens holder comprises a material that is opaque to light within a specific wavelength range.
4. The optical finger navigation device of claim 1 , wherein the lens is disposed in the lens holder with an adhesive.
5. The optical finger navigation device of claim 1 , wherein the molded lead frame further comprises a lead frame.
6. The optical finger navigation device of claim 5 , wherein the light source and the sensor are disposed on and electrically connected to the lead frame.
7. The optical finger navigation device of claim 1 , wherein the at least one surface extending between the input and the output is slanted at a non-normal angle relative to a major surface of the lens holder.
8. The optical finger navigation device of claim 1 , wherein there is no collimating lens located between the light source and the navigation surface.
9. An optical finger navigation package comprising:
a molded lead frame sub-assembly comprising a quad fiat pack no-lead (QFN) lead frame, a base having a plurality of pins, a light source, and a sensor; and
a lens holder sub-assembly comprising a lens, a lens receiving region, a plurality of through holes configured to mate with the plurality of pins of the base, and a light guide system;
wherein the light guide system is configured to direct light emitted by the light source towards a navigation surface in a light path that extends from the light source to the navigation surface;
wherein the light guide system comprises an aperture system that defines a cavity that passes through the lens holder sub-assembly, that is aligned with the light source, and that is configured to direct the emitted light from the light source towards the navigation surface in the light path;
wherein the plurality of pins and the plurality of through holes mate together via a heat staking process, and wherein each of the plurality of pins passes through a corresponding through hole of the plurality of through holes and an end portion of the each of the plurality of pins is protruded from the corresponding through hole, and during the heat staking process the plurality of pins is heated and the end portion of each of the plurality of pins is deformed into a protrusion that has a diameter larger than a diameter of the plurality of pins such that the protrusion become a lock structure and the plurality of pins is locked within the plurality of through holes, respectively; and
a lens coupled to the lens receiving region of the lens holder sub-assembly and configured to direct light from the navigation surface towards the sensor.
10. The optical finger navigation system of claim 9 , wherein the cavity comprises an input opening nearest the light source where the emitted light enters the cavity and an output opening nearest the navigation surface where the emitted light exits the cavity, wherein the aperture system that defines the cavity comprises at least one surface extending between the input and the output of the cavity, the at least one surface being slanted at an angle to reflect at least a portion of the emitted light towards the navigation surface, and wherein there is no illumination lens located in the entire light path between the light source and the navigation surface.
11. An optical finger navigation system, comprising:
a light source configured to emit light;
a light sensor configured to receive light from a navigation surface;
a molded lead frame comprising a lead frame and a base having a plurality of pins;
a single lens configured to direct light from the navigation surface toward the light sensor; and
a lens holder molded to form a unitary structure, the lens holder comprising:
a lens receiving region configured to receive and retain the single lens;
a light guide system that directs the emitted light toward the navigation surface in a light path that extends from the light source to the navigation surface; and
a plurality of through holes configured to mate with the plurality of pins of the base, wherein the plurality of pins and the plurality of through holes mate together via a heat staking process, and wherein each of the plurality of pins passes through a corresponding through hole of the plurality of through holes and an end portion of the each of the plurality of pins is protruded from the corresponding through hole, and during the heat staking process the plurality of pins is heated and the end portion of each of the plurality of pins is deformed into a protrusion that has a diameter larger than a diameter of the plurality of pins such that the protrusion becomes a lock structure and the plurality of pins is locked within the plurality of through holes, respectively.
12. The optical finger navigation system of claim 11 , wherein the light source and the sensor are disposed on and electrically connected to the molded lead frame.
13. The optical finger navigation system of claim 11 , wherein the single lens is disposed in the lens holder with an adhesive.